Reverse cycle refrigeration apparatus



Novl- 24, 1964 A. E. sKEATs E'rAL 3,158,006 REvERsE CYCLE RERRIGERRT-ION APPARATUS- Eiled oct. so, 196s faz J6) 70 5 j f l a6 h-7J J l fr u i 51"' 132 33 fai y 30 K'L rl x Z6 29 f 63 L* Afd.. @223 ff /jg 67 6j 6? Ll 60 P39 1 6g" f /`52 46) 4j zg X f -E *a* .0

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United States Patent O 3,153,006 REVEE CYCLE REFREGERATIQN AEPTUS Alfred E. Skeats, Spring Garden Township, York County, .lohn C. leier, York Township, York County, and Merle A. Clark, West Manchester 'ownshp Yori( County, Pa., assignors to Borg-Warner Corporation, Chicago, lll., a corporation of lliinois Filed Het. 3th, 1963, Ser. No. 323,146 6 Ciairns. (Qi. :S2-324) This invention relates to improvements in closed circuit, reverse cycle refrigeration apparatus or heat pumps of the type especially adapted for use in year-around airconditioning systems. The invention is more particularly concerned with a unit having an outside heat exchanger `and an inside heat exchanger in combination with means for reversing refrigerant llow between said heat exchangers to selectively provide cooling or heating depending on whether the inside heat exchanger is functioning as an evaporator or a condenser.

Apparatus of the aforementioned class generally includes `a compressor, a pair of expansion valves or capillary elements, a pair of check valves and a reversing valve. These elements are connected with the inside and outside heat exchangers to permit operation of the system in both the heating mode and the cooling mode. When heating is required, the inside heat exchanger functions as a condenser discharging heat to the air circulating inside the room, and the outside heat exchanger functions as an evaporator. When cooling is required, the inside heat exchanger functions as an evaporator and the outside heat exchanger functions as -a condenser, rejecting @ne common design includes a pair ot conduits connected in parallel between the two heat exchangers with a separate expansion valve in each line. cludes a check valve permitting ilow in one direction only so that during one mode of operation, the check valve permits ow from the condensing heat exchanger through the expansion valve to the evaporating heat exchanger while the check valve in the other conduit blocks ow through said conduit from the evaporating heat exchanger to the condensing heat exchanger thereby rendering the other expansion valve inoperative.

A number of problems are associated with this type ot system. First of all, the expansion valves have control bulbs respectively associated with two different lines which alternately interconnect with the suction and discharge side of the compressor. Consequently, each of the expansion valve control bulbs is responsive to the temperature of a line which is alternately conducting hot gas from and cold gas to the compressor. This wide variation in temperatures and the corresponding pressures acting on the expansion valve diaphragms quite obviously has a detrimental effect on their operational life.

Another factor is the effective location of the lterdrier means conventionally employed to absorb moisture and lter dirt and other foreign materials from the refrigerant. Ideally, the filter-drier should be placed between the condensing heat exchanger and the expansion valve. inasmuch as the most effective ilter-drier means are unidirectional in operation, the system described above either requires the use of two separate ilter-drier elements or the omission of a single filter-drier from the circuit during either the heating cycle or the cooling c cle.

yAnother known apparatus avoids some of these problems by using one reversing valve and another valve which may be regarded as a tlow control valve, the latter being responsive to the pressure differential across the One disadvantage of this system is that the flow control valve must be designed to insure opera- In this arrangement, each conduit also in- 3,158,006 Patented Nov. 24, 1964 ICC tion over a wide range of condensing temperatures. Moreover, there is the inherent possibility of a considerable time lag between the actuation of the reversing valve and the subsequent switchover of the flow control valve.

It is therefore a principal object of the invention to provide an improved reverse cycle refrigeration system having increased reliability and quick response to actuation of the master reversing Valve.

Another object of the invention is to provide a reverse cycle refrigeration system which avoids wide variations in the pressure acting on the expansion valve diaphragm.

Additional objects and advantages will be apparent from a reading of the following detailed description taken in conjunction with the appended drawings wherein:

FIGURE 1 is a schematic diagram illustrating the refrigeration circuit in the heating mode; and

FIGURE 2 is a schematic diagram illustrating the refrigeration circuit in the cooling mode.

Referring now to FIGURE l, a preferred embodiment of the invention includes a first heat exchanger 10, a second heat exchanger 12, a compressor 14, and a refrigeration circuit including a first reversing valve 16, a second reversing valve 18, a pilot valve 19, a lter-drier means 2li and an expansion valve 22. Heat exchangers 10 and 12 are arranged so that their respective functions, i.e., evaporating and condensing, are adapted to be interchanged by reversing the direction of refrigerant ow through the system. For purposes of illustration, it will be assumed that the apparatus is employed in a typical comfort air conditioning system and that heat exchanger it) is the inside coil and heat exchanger 12 is the outside coil.

Compressor 14, which may be of any conventional design', has a suction side and a discharge side, the latter being liuidly interconnected to a port 25 in reversing valve 16 through conduit means 23. Reversing valve 16, the master valve, comprises a hollow casing 26 and a slidable spool member 27 received therein. The casing 26 is provided with control pressure ports 342, 35 at opposite ends of the casing, said ports cooperating with the pilot valve 19 to move the spool member 27 in a manner to be larly, the po1t 2S is adapted to be selectively interconnected to either port 31 or port 33 through huid passage means 2S and 30, respectively, in spool member 27.

Reversing valve 18, the slave valve, is of the same general design as reversing valve 16, and comprises a casing 36 including control pressure ports 55, S7 and refrigerant ports d1, 42, 43, and 44, and a slidable spool member 37 having lluid passage means 33, 39, and 40 provided therein. solenoid actuated type and includes a port 60, communieating at all times with compressor suction pressure through line 61, and additional ports 62,` 63 respectively communicating with control pressure ports 34, 35 in valve 16 lthrough lines 64, 65. The position of pilot valve element 66, which is controlled by solenoid 67, determines the position of spool member 27 in the master reversing valve 16 by selectively interconnecting either control pressure port 34 or control pressure port 35 with compressor suction.

The circuit connecting the reversing valves, the compressor, and the heat exchangers includes conduit means d5' connecting port 33 in valve 16vto heat exchanger 10; conduit means 46 connecting heat exchanger 10 with 43 with the filter-drier means 20; conduit means 49 con- The pilot valve 19 may be of the necting filter-drier means 2i) to the expansion valve 22; conduit means 5t) connecting the expansion valve with port 41 in valve 18; conduit means 52 connecting port 42 in valve 1S with heat exchanger 12; conduit means 54 connecting heat exchanger 12 with port 31 in valve 16; conduit means 56 connecting port 32 in valve 16 to the suction side of the compressor; conduit means '7G connecting control pressure port 55 with conduit means 54; and conduit means 71 connecting control pressure port 57 with conduit means 45. Thermal sensing bulb 58 for expansion valve 22 is associated with conduit means 56, which constitutes the compressor suction line regardless of whether the unit is operating in the heating or cooling mode.

Operation Referring irst to FIGURE l, to operate the unit in the heating mode, the solenoid 67 is energized to move the pilot valve element 66 against the opposition of the spring thereby positioning said element so that port 62 is in iiuid communication with the suction pressure port 60. Suction is thus applied to control pressure port 34 in the master reversing valve 16 through conduit means 61 and 64. Since the other control pressure port 35 is closed, the suction applied at port 34 moves the valve spool member to the left to assume and maintain the position illustrated in FIGURE 1. The hot refrigerant gas discharged from the compressor flows to the inside heat exchanger 19 via conduit means 3, fluid passage means 3Q, and conduit means 45. At the same time, gas under pressure is supplied through line 71 to control pressure port 57 in the slave reversing valve 18 thereby shifting and maintaining the spool in the position shown in FIGURE l. Refrigerant flow continues through the passage 40 in spool member 37, conduit means 48, the filter-drier means 20, expansion valve 22 and line 52 to heat exchanger 12 which is functioning as an evaporator. Thereafter, the cold, low-pressure refrigerant gas returns to the suction side of the compressor through conduit means 54, liuid passage means 29 in spool member 27 and conduit means 56. When the system is switched over to the cooling cycle, solenoid 67 is de-energized to elTect iuid communication between the suction side of the compressor and control pressure port 35 in master reversing valve 16. This causes the spool member to shift to the right to assume and maintain the position shown in FIGURE 2.

Simultaneously, the hot gas discharge line is shifted from line 45 to line 54 thereby supplying hot gas through line 70 to the control pressure port 55 in the slave reversing valve 18. Retrigerant tiows through heat exchanger 12, conduit means 52, i'luid passage means 3S, filter-drier means 2t), expansion valve 22, conduit means Si?, fluid passage `means 39 and conduit means 46 to the inside heat exchanger now functioning as an evaporator. Cold gas is returned through conduit means 45, fluid passage means 29 in the valve spool 27 through conduit means S6 to the suction side of the compressor.

It will be apparent from the foregoing description that the advantages of maintaining refrigerant ow through the ilterdrier and the expansion valve element are combined with the quick response achieved by utilizing hot gas pressure from the compressor to actuate the slave reversing valve.

While this invention has been described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of this invention is defined solely by the appended claims which should be construed as broadly as the prior art will permit.

What is claimed is:

l. In a closed circuit, reverse cycle refrigeration apparatus:

a compressor;

an inside heat exchanger;

an outside heat exchanger;

a refrigeration circuit connecting said compressor and said inside and outside heat exchangers, said circuit comprising:

a first reversing valve adapted to selectively and alternately direct refrigerant gas discharged from said compressor to said inside heat exchanger or said outside heat exchanger;

conduit means including, in series, a filter-drier means and an expansion valve;

a second reversing valve interconnecting said inside heat exchange', said outside heat exchanger and said conduit means, said second reversing valve being arranged to reverse tlow of refrigerant between said inside heat exchanger and said outside heat exchanger through said conduit means while maintaining refrigerant ow through said conduit means in the same direction regardless of the direction of the refrigerant iiow between said inside and outside heat exchangers;

means for actuating said first reversing valve; and

means associated with said rst reversing valve to selectively direct high pressure refrigerant gas to said second reversing valve, said gas being effective to actuate said second reversing valve whereby said second reversing valve is actuated in response to said first reversing valve.

2. An apparatus as delined in claim 1 wherein said first reversing valve includes a slidable spool member and a pair of control pressure ports, said spool member and said control pressure ports being arranged so that the position of said spool member is a function of the pressure diterential between said control ports.

3. An apparatus as defined in claim 2 wherein said means for actuating said first reversing valve comprises a pilot valve adapted to selectively and alternately interconnect said control pressure ports with compressor suction pressure.

4. In a closed circuit, reverse cycle refrigeration system, the combination comprising:

a compressor having a discharge side and a suction side;

a rst heat exchanger;

a second heat exchanger;

a first reversing valve having a refrigerant port connected to the discharge side of said compressor and a slidable spool member having tiuid passage means adapted to selectively and alternately interconnect said port with said first heat exchanger or said second heat exchanger, said spool element having additional uid passage means adapted to Se lectively and alternately interconnect said second heat exchanger or said first heat exchanger with the suction side of said compressor;

conduit means including a iilter-drier means and an expansion valve means, said expansion valve means being responsive to the temperature of cold refrigerant gas on the suction side of said compressor;

a second reversing valve having a slidable spool member which is provided with tiuid passage means adapted to selectively and alternately interconnect said first and second heat exchangers through said conduit means, said second reversing valve being effective to reverse the iiow of refrigerant between said irst heat exchanger and said second heat exchanger without changing the direction of refrigerant flow through said conduit means; and

means for conducting compressor discharge gas to said second reversing valve to move the spool member in said second reversing valve means in response to the direction of the refrigerant gas ow from said compressor, whereby a shift in the position of the spool member in said trst reversing valve effects a correspondngshift in the position of the spool member in said second reversing valve.

5. In a system as delined in claim 4, means for selectively subjecting the spool member in said first re- 5 o versing valve to compressor suction pressure, whereby means defining a pair of control pressure ports in said said spool member is shifted by said suction pressure. second reversing valve adapted to selectively supply 6. In a system as defined in claim 4: high pressure refrigerant gas to yopposite ends of the means defining a pair of control pressure ports in said spool member in said second reversing valve.

tir-st reversing Valve; 5 a pilot valve connected to the suction side of said corn- Y Rert-QS Ci in the e Of hS Patent PSSOY; UNETED STATES PATENTS conduit means connecting each of seid control pressure sure ports with the suction side of said compressor; and 

1. IN A CLOSED CIRCUIT, REVERSE CYCLE REFRIGERATION APPARATUS: A COMPRESSOR; AN INSIDE HEAT EXCHANGER; AN OUTSIDE HEAT EXCHANGER; A REFRIGERATION CIRCUIT CONNECTING SAID COMPRESSOR AND SAID INSIDE AND OUTSIDE HEAT EXCHANGERS, SAID CIRCUIT COMPRISING: A FIRST REVERSING VALVE ADAPTED TO SELECTIVELY AND ALTERNATELY DIRECT REFRIGERANT GAS DISCHARGED FROM OR SAID COMPRESSOR TO SAID INSIDE HEAT EXCHANGER OR SAID OUTSIDE HEAT EXCHANGER; CONDUIT MEANS INCLUDING, IN SERIES, A FILTER-DRIER MEANS AND AN EXPANSION VALVE; A SECOND REVERSING VALVE INTERCONNECTING SAID INSIDE HEAT EXCHANGER, SAID OUTSIDE HEAT EXCHANGER AND SAID CONDUIT MEANS, SAID SECOND REVERSING VALVE BEING ARRANGED TO REVERSE FLOW OF REFRIGERANT BETWEEN SAID INSIDE HEAT EXCHANGER AND SAID OUTSIDE HEAT EXCHANGER THROUGH SAID CONDUIT MEANS WHILE MAINTAINING REFRIGERANT FLOW THROUGH SAID CONDUIT MEANS IN THE SAME DIRECTION REGARDLESS OF THE DIRECTION OF THE REFRIGERANT FLOW BETWEEN SAID INSIDE AND OUTSIDE HEAT EXCHANGERS; MEANS FOR ACTUATING SAID FIRST REVERSING VALVE; AND MEANS ASSOCIATED WITH SAID FIRST REVERSING VALVE TO SELECTIVELY DIRECT HIGH PRESSURE REFRIGERANT GAS TO SAID SECOND REVERSING VALVE, SAID GAS BEING EFFECTIVE TO ACTUATE SAID SECOND REVERSING VALVE WHEREBY SAID SECOND REVERSING VALVE IS ACTUATED IN RESPONSE TO SAID FIRST REVERSING VALVE. 